What is recommended for the vessel for purification in the washroom

Abū Jaʿfar Muḥammad b. Manṣūr said: I saw in the wuḍū-place of Aḥmad b. ʿĪsā a brass jug with a wide head, distant from the washroom by a little, and above the jug there was a small jug. When he wanted to do istinjā he would scoop with the small jug from the large jug. So when he was satisfied he would return the small jug on the head on the large one.

He said: And I saw for him in the front of the house of the wuḍū-place, a seat upon which he would sit. It had a stair or two stairs, and to the side of the chair there was a brass vessel on something elevated. And there was a wooden cap for the vessel in proportion to the head of the vessel which had a mamkan (?). So when he sat on the chair, the vessel would be to his right. And the washroom was in back of the house. And the kerchief was hanging close to the chair.